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|
use std::fmt::{self, Debug, Formatter};
use super::*;
#[cfg(feature = "layout-cache")]
use {
fxhash::FxHasher64,
std::any::Any,
std::hash::{Hash, Hasher},
};
/// A tree of layout nodes.
pub struct LayoutTree {
/// Runs of pages with the same properties.
pub runs: Vec<PageRun>,
}
impl LayoutTree {
/// Layout the tree into a collection of frames.
pub fn layout(&self, ctx: &mut LayoutContext) -> Vec<Rc<Frame>> {
self.runs.iter().flat_map(|run| run.layout(ctx)).collect()
}
}
impl Debug for LayoutTree {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.debug_list().entries(&self.runs).finish()
}
}
/// A run of pages that all have the same properties.
#[derive(Debug)]
pub struct PageRun {
/// The size of each page.
pub size: Size,
/// The layout node that produces the actual pages (typically a
/// [`StackNode`]).
pub child: LayoutNode,
}
impl PageRun {
/// Layout the page run.
pub fn layout(&self, ctx: &mut LayoutContext) -> Vec<Rc<Frame>> {
// When one of the lengths is infinite the page fits its content along
// that axis.
let expand = self.size.to_spec().map(Length::is_finite);
let regions = Regions::repeat(self.size, self.size, expand);
self.child.layout(ctx, ®ions).into_iter().map(|c| c.item).collect()
}
}
/// A dynamic layouting node.
pub struct LayoutNode {
node: Box<dyn Layout>,
#[cfg(feature = "layout-cache")]
hash: u64,
}
impl LayoutNode {
/// Create a new instance from any node that satisifies the required bounds.
#[cfg(not(feature = "layout-cache"))]
pub fn new<T>(node: T) -> Self
where
T: Layout + 'static,
{
Self { node: Box::new(node) }
}
/// Create a new instance from any node that satisifies the required bounds.
#[cfg(feature = "layout-cache")]
pub fn new<T>(node: T) -> Self
where
T: Layout + Hash + 'static,
{
let hash = {
let mut state = FxHasher64::default();
node.type_id().hash(&mut state);
node.hash(&mut state);
state.finish()
};
Self { node: Box::new(node), hash }
}
}
impl Layout for LayoutNode {
fn layout(
&self,
ctx: &mut LayoutContext,
regions: &Regions,
) -> Vec<Constrained<Rc<Frame>>> {
#[cfg(not(feature = "layout-cache"))]
return self.node.layout(ctx, regions);
#[cfg(feature = "layout-cache")]
ctx.layouts.get(self.hash, regions).unwrap_or_else(|| {
ctx.level += 1;
let frames = self.node.layout(ctx, regions);
ctx.level -= 1;
let entry = FramesEntry::new(frames.clone(), ctx.level);
debug_assert!(
entry.check(regions),
"constraints did not match regions they were created for",
);
ctx.layouts.insert(self.hash, entry);
frames
})
}
}
impl Debug for LayoutNode {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
self.node.fmt(f)
}
}
#[cfg(feature = "layout-cache")]
impl Hash for LayoutNode {
fn hash<H: Hasher>(&self, state: &mut H) {
state.write_u64(self.hash);
}
}
|
